Ultrasonic welding first appeared in the early 1990s and continues to rapidly develop. In the infancy of ultrasonic welding, only hard plastics could be welded because only hard plastics had the properties prerequisite for the ultrasonic welding process—such hard plastics materials were acoustically conductive and had a low melting point. Less rigid plastics such as semicrystalline plastics can be welded today.
In order to weld materials together using conventional processes, the materials to be welded must be in compatible groups. Incompatible groups can not utilize the technique of ultrasonic welding. Examples of incompatible groups of materials that can not be ultrasonically welded using conventional processes include but are not limited to polycarbonates with PVC, acrylics with PVC, and usually, crystalline/semi-crystalline materials with amorphous materials.
In order to bond materials from incompatible groups it is necessary to use adhesives, solvents, as well as, mechanical means including sewing or stitching, riveting and stapling. However, none of these techniques create a union between the actual materials being bonded and thus present limitations including weakness and porosity in addition to detrimental environmental issues.
Therefore, there is a need for a system and method for ultrasonic welding of traditional incompatible materials.